Drupal 7 tip : Update and insert only specific fields of your entity

If you want to save only a specific field on your entity instead of saving the whole entity you can. In a submodule of the fields module you ll find a module called field_sql_storage module. In that module all functions available for the sql storage backend can be used. One of them is field_sql_storage_field_storage_write, which you give your entity, type, operator (update, insert) and which fields to save.